In this paper, we analyze the tourism efficiency of Croatian counties using data envelopment analysis DEA with the purpose of identifying counties which are efficient and which represent successful examples of tourism performance benchmarking as well as inefficient counties whose inefficiency should be minimized by undertaking certain necessary measures. Comparison of the results using models with constant and variable returns to scale has given preference to the BCC model, and the output-oriented model has been chosen. Sources and amounts of relative inefficiency were identified for each input and output, and guidelines for necessary improvements were given. As an extension of the basic model, we introduced window analysis which examines efficiency over five years, i.e., through one five-year and five one-year periods.